Cellular structure and method of manufacture



v. J. BARUT 3,018,205 CELLULAR STRUCTURE AND METHOD 0? MANUFACTURE 2 Sheets-Sheet 1 Jan. 23, 1962 Filed Feb. 9, 1959 Jan. 23, 1962 v. JIBARUT 3,

CELLULAR STRUCTURE AND METHOD OF MANUFACTURE Filed Feb. 9, 1959 2 Sheets-Sheet 2 United States Patent 3,018,205 CELLULAR STRUCTURE AND METHOD OF MANUFACTURE Victor Jacques Barut, 4 Rue de Civry, Paris, France Filed Feb. 9, 1959, Ser. No. 792,134 Claims priority, application France Feb. 25, 1958 6 Claims. (Cl. 154-45) The present invention relates to a honeycomb or cell structure of the type employed especially for the fillings or linings of various kinds of constructions known as sandwiches, panels, partitions, etc. for the building trade, aircraft construction, etc.

A large number of structures of this kind are already known, from square or rectangular networks obtained by means of notched strips or hands assembled together, to various geometrical shapes produced by means of glued bands. Amongst these latter, some are obtained by means of bands previously shaped so as to form halfhoneycomb structures of any shape, and successive bands are glued together at their areas of contact. Others are produced by means of bands which are glued while flat, with staggered gluing zones, this operation being followed by an expansion which results in the unfolding of the cells between the glued zones.

Each kind of cell structure with glued bands has its advantages and its drawbacks.

Pro-forming makes it possible to give the cells varied geometrical patterns, but their manufacture is complicated and costly; this method of construction is therefore very little used. From the economic point of view, the preference goes to the structures which are obtained by gluing when flat and which are subsequently expanded. But in practice this method of procedure limits the structure to a substantially hexagonal form known as a honeycomb. In addition, the expansion reduces the width with respect to that of the initial block before expansion. Furthermore, the expansion does not take place in a uniform manner; it is more pronounced at the ends than at the centre, and the structure tends to have a concave profile along its longitudinal edges.

The present invention has for its object a structure of the kind consisting of bands or sheets which are glued and subsequently expanded, which not only avoids these disadvantages while keeping the manufacture simple and cheap, but after expansion provides panels having a width which is at least twice that of the original block.

This structure is characterised in that it is composed of bands having alternating folds in the shape of two Zs joined back to back and glued to each other on the lower and upper faces of the folds.

Double folds are understood to mean folds of the type commonly referred to as box pleats, in which the band comprises alternately a fold in one direction and a fold in the other direction. Ina particular form of this double pleat, two equal lengths of the band are coupled together by a smaller element, the length of which is at least equal to half the length of the band; the successive bands are superimposed with a respective shift corresponding to this half-length.

The gluing is effected by two lengths arranged one on the other, having in practice a displacement or shift of one band by one half-length with respect to the adjacent band, or by supplying from two different folding machines.

The structure thus formed is expanded by a tractive pull on its opposite edges. The maximum expansion in a given direction gives rise to a unit having square or rectangular cells, the sides of which are displaced by one row with respect to the next. When expanded, it is found that both the length and width of this structure are increased at the same time.

3,018,205 Patented Jan. 23, 1962 This structure is produced by gluing while flat. It may be obtained by the use of bands or sheets, the sheets or bands being folded and then glued and expanded. When sheets are used, the product obtained may be cut up into sections before expansion.

This manufacturing process may be carried out in a continuous manner. For the folding operation, the machines which are usually employed for folding textile fabrics may be used. The gluing and the subsequent cutting-out operation are carried out by the usual means.

The accompanying drawings show the structure in accordance with the invention, and one of its methods of manufacture.

FIG. 1 is a view of the structure before expansion.

FIG. 2 shows the structure normally expanded.

FIG. 3 shows a further method of expansion.

FIG. 4 is a view illustrating the method of construction.

FIG. 5 is a diagrammatic view of the manufacturing process.

The structure in accordance with the invention is formed by a succession of glued bands. Each band has a double fold, that is to say, comprising: a portion 10 having a length a, two portions 11 having a shorter length, folded back on the portion 10 and attached to a portion 12 having a length a, which is itself coupled to the next portion 10 by a fold 11. The bands thus folded are placed side by side, and the portion 10 of one band is glued to the portion 12 of the preceding band.

The assembly of the glued bands together thus cornprises incipent cells, each in the form of an irregular convex hexagon, each hexagon having the portions 1012 as its long opposite sides, and the folds 11 as its small lateral sides.

The portions 11 may be more or less pronounced. It is on the length of these portions that the final expansion of the structure depends.

These portions 11 are preferably given a length which is substantially equal to half the length a of the portions 10 and 12.

When the structure is pulled out in the direction of the arrows A, at right angles to the bands, it takes the shape shown in FIG. 2, forming at its maximum expansion a network of rectangular or square cells 13, the sides of which have the length a of the portions Ill-12 and twice the length of the portions 11, that is to say this length is also a if the length of the portions 11 is a/2. These cells are aligned in rows touching each other. Each row is displaced from that adjoining by the length of half the side 11. The sides of each cell are formed on the one hand by the portions 10 and 12 of two adjacent bands which are glued together; on the other hand, by the portions 11 forming the folds which are straightened out in alignment.

It is to be observed that if, starting from FIG. 2, the cellular structure is drawn-out in the direction of the arrows B-B and parallel to the bands, this produces hexagonal cells as shown in FIG. 3, although the hexagons are irregular, the sides 11 being of shorter length than the opposite sides 10-12.

The structure which has just been described may be made of any material: cardboard, paper (whether impregnated or not), metal, plastic material, etc. The gluing operation may be carried out by using any of the usual adhesives, or alternatively by a thermo-plastic effect. If the material used is a metal, the joint may be effected by welding or brazing.

The structure in its expanded form is used as a filling or lining for all uses that may be desired. It may be associated with coverings of all materials: plywood, metal, plaster, plaster-board (known as Placoplatre), asbestoscement, etc., so as to form panels, partitions or other constructional members.

A structure of this kind has excellent properties of strength, and especially of a uniformstrengthat all its points, by reason of the regular and intersected alignment of the square cells.

It may be constructed by starting with bands 20 (FIG. 4), in which are formed the folds 21, 22 of opposite directions by a folding process.

The length of the portions 11 should preferably be chosen so as to be equal to half the length of the portions or 12. In this Way, the two foldsll are folded back on 12 so as completely to overlap the necessary portions 12.

A coating 23 of adhesive (and especially of glue), is laid on the band thus folded, and a further identical band is laid on to the glue. This second hand is however displaced or reversed with respect to the first, so that its portions 10 are glued to the portions 12 of the preceding band 20.

The band 20' is then coated with glue at 23' in order to receive a further band 20" and so on.

"Instead of starting with bands, and this method is generally more efiective, it is possible to start with sheets 24 (FIG. 5) supplied from a roller 25 and guided by rollers 2627.

The sheet 24 passes between the blades 28-29 (which are suitably spaced apart) to which are given motions adapted to form double folds as shown at 30.

The sheet 30 thus folded receives a coating of glue from the roller 31. It is then cut-off transversely into elements of suitable length and these elements fall into a central passage in which they are superimposed one on the other with the required displacement, and are glued to each other at 32.

The assembly of sheet elements thus fixed together is then cut-off along the lines 33 which are separated by the distance which corresponds to the thickness of the structure to be produced. Blocks are thus obtained which are then expanded as explained above and as shown in FIGS. 2 and 3.

It will of course be understood that the method of manufacture which has been described and shown has no restrictive nature, and any other method of operation could be adopted without thereby departing from the spirit or the scopeof the present invention.

What I claim is:

1. A cellular structure comprising a plurality of strips each having a plurality of elongated sides of equal length in one plane, a plurality of further elongated sides of the same equal length as said elongated sides in another plane parallelly spaced from said one plane, angular sides which are half the length of said elongated sides connecting one end of each of said elongated sides with an adjacent end of said further elongated sides to form box pleats, each strip of box pleats placed adjacent a Succeeding strip of box pleats such that said elongated-sides of each strip are attached throughout their entire area to said further elongated sides of an adjacent strip thereby forming a-plurality of flexible areas in said structure consisting of an elongated side of one strip, a coextensive further elongated side of an adjacent strip, and their respective angular sides, and said structure being expansible simultaneously in two directions atright angles to each other through triangular rectangular, and hexagonal afirst series of straight sides of equal length disposed in a first plane, a second series of straight sides of the same length as said first series of straight sides disposed in a second plane spaced from and parallel to said first plane,

a plurality of angular sides which are half the lengthof said first and second series of straight sides interconnecting 'said first and second series of straight sides such that one end of an angular side is connected to one end of one side of said first seriesof straight'sides while the other end of said angular side is connected to one end of one side of said second series of straight sides which is contiguous to the one side of said first series of straight sides, each element capable of being flattened so that each angular side has one surface in contact with the inner surface of the side of said first series of straight sides to which it is connected and the other surface in contact with the inner surface of the side of said second series of straight sides to which it is connected, the sidesof each of said first series of straight sides connected substantially throughout their entire area to the adjacent sides of said second series of straight sides, and said structure being expansible simultaneously in two different directions at right angles to each other to a hexagonal configuration.

3. A cellular structure comprising a plurality of bands attached to each other throughout said structure at designated areas, each band folded at predetermined transverse places to form box pleats consisting of a plurality of first longitudinal segments of equal length, a plurality of second longitudinal segments of the same length as said first longitudinal segments, said second longitudinal segments spaced in offset relationship from said first longi-tudinal segments, one end of one of said first longitudinal segments connected to one end of an angular segment of half the length of said longitudinal segments, the other end of said angular segment connected to one end of one of said second longitudinal segments adjacent to the one of said first longitudinal segments, each of the other ends of said first and second longitudinal .segments connected by an angular segment in like manner throughout each band to form dove-shaped corrugations therein, said first longitudinal segments of each band attached throughout its entire area to said second longitudinal segments of an adjacent band of said cellular structure such that the base of each band is coextensive with the base of each adjacent band, and after formation said structure being expansible simultaneously in two directions at right angles to each other through triangular, rectangular, and hexagonal configurations.

4. A cellular structure comprising a plurality of elements having dovetai-l shaped corrugations consisting of top portions and bottom portions of equal length and connecting angular sides of half the length thereof, each top portion of each element is attached in coextensive manner throughout its entire area to each bottom portion of an adjacent element, each bottom portion of each elementis coextensive with each top portion of each .element of an adjacent element upon being folded fiat, a plurality of flexible areas define-d and delimited by the coextensive top and bottom portions along with their connecting sides throughout said structure, and said structures being expansible in two directions at right angles to each other while each flexible area therein is distorted through triangular, rectangular, and. hexagonal configurations.

5. A method of manufacture of cellular structure comprising the steps of transversely folding sheets of material into dovetail-shaped corrugations consisting of top surfaces and bottom surfaces of equal length and connecting angular sides of half the length of said top and bottom surfaces, attaching the top surfaces of one sheet of material to the bottom surfaces of an adjacent sheet of material throughout their entire area such that each "bottom surface of each sheet of material is coextensive with a top surface of an adjacent sheet of material and a plurality of flexible areas is formed by the top and bottom surfaces along with their respective sides throughout the cellular structure, and simultaneously unfolding the structure in two directions at right angles to each other forming successively triangular, rectangular, and hexagonal configurations.

6. A method according to claim 5 which comprises cutting the attached sheets at right angles to the transverse folds forming the dovetail-shaped corrugations at prede- References Cited in the file of this patent UNITED STATES PATENTS Lantzke July 14, 1896 6 Ford Feb. 4, 1919 Olson Aug. 27, 1929 Steele et a1 Apr. 6, 1954 FOREIGN PATENTS Italy 1 Sept. 20, 1949 Canada May 15, 1956 

1. A CELLULAR STRUCTURE COMPRISING A PLURALITY OF STRIPS EACH HAVING A PLURALITY OF ELONGATED SIDES OF EQUAL LENGTH IN ONE PLANE, A PLURALITY OF FURTHER ELONGATED SIDES OF THE SAME EQUAL LENGTH AS SAID ELONGATED SIDES IN ANOTHER PLANE PARALLELLY SPACED FROM SAID ONE PLANE, ANGULAR SIDES WHICH ARE HALF THE LENGTH OF SAID ELONGATED SIDES CONNECTING ONE END OF EACH OF SAID ELONGATED SIDES WITH AN ADJACENT END OF SAID FURTHER ELONGATED SIDES TO FORM BOX PLEATS, EACH STRIP OF BOX PLEATS PLACED ADJACENT A SUCCEEDING STRIP OF BOX PLEATS SUCH THAT SAID ELONGATED SIDES OF EACH STRIP ARE ATTACHED THROUGHOUT THEIR ENTIRE AREA TO SAID FURTHER ELONGATED SIDES OF AN ADJACENT STRIP THEREBY FORMING A PLURALITY OF FLEXIBLE AREAS IN SAID STRUCTURE CONSISTING OF AN ELONGATED SIDE OF ONE STRIP, A COEXTENSIVE FURTHER ELONGATED SIDE OF AN ADJACENT STRIP, AND THEIR RESPECTIVE ANGULAR SIDES, AND SAID STRUCTURE BEING EXPANSIBLE SIMULTANEOUSLY IN TWO DIRECTIONS AT RIGHT ANGLES TO EACH OTHER THROUGH TRIANGULAR, RECTANGULAR, AND HEXAGONAL CONFIGURATIONS. 